Method of assembling crystals in watch bezels



Aug. 19, 1952 O STARKE 2,607,082

METHOD OF ASSEMBL'ING CRYSTALS IN WATCH BEZELS Filed July 51, 1947INVENTOR.

BY @WMQ ATTORN EY Patented Aug. 19, 1952 Lamar METHOD OF ASSEMBLINGCRYSTALS IN WATCH BEZELS Otto A. Starke, Ludington, Mich., assignor toStar Watch Case Company, Ludington, Mich.

' Application July 31, 1947, Serial No. 764,978

6 Claims. 1

This invention relates to improvements in the method of assemblingcrystals in Watch bezels.

The principal objects of this invention are:

First, to provide a watch crystal and bezel for holding the crystal on awatch which will effectively seal the crystal. and bezel against theentrance of moisture and dirt.

Second, to provide a watch crystaland bezel assembly which may be easilyassembled without producing visible scratches on the crystal.

- Third, to provide a method of assemblin an unbreakable watch crystalon a bezel so that the crystal cannot belost.

Fourth, to provide a watch crystal which cannot. be pushed against therace of the watch and damage the watch movement.-

Fiith. to provide a method for inexpensively sealingathermoplastic,watch crystal to a bezel.

.Other objects and advantages relating to the details and economiesofthe invention will be apparent from the following description andclaims.

Thedrawings, of which there is one sheet, illustrate three forms of mywatch crystal as assembled ina bezel and certainsteps in the assemblythereof.

Fig. 1 is a plan. view of a wrist watch case.

Fig. 2 is a fragmentary cross sectional view through the crystal andbezel along the line 22 in Fig. 1.

- Fig. 3 is a fragmentary cross sectional view of a modified form ofcrystal and bezel.

' Fig. 4 is an enlarged fragmentary cross sectional view showing onestep in the assembly of my crystal and bezel.

Fig. 5 is a view similar to Fig. 4 showing a third form of my crystaland its method of assembly.

Fig. 6 is an elevational view illustrating conventionally a step in theassembly of my crystal and bezel.

The drawings illustrate a watch case I having a bezel 2 arranged to besecured to and support a crystal 3. As is more particularly shown in thecross sectional views the bezel 2 is provided .with a rearwardlyextending flange 4 arranged to be snap fitted to the ring of the watchcase in the usual fashion and a radially inwardly extending flange 5arranged to engage the crystal. Preferably the flange 5 slopes slightlyforwardly of the crystal opening. The drawings illustrate a case andbezel of quadrilateral contour having curved sides but obviously othercontours and other decorative flange and shoulder arrange ments such asthe shoulders 6 may be devised. The bezel has no reflector portion.

The crystal 3 is made of unbreakable plastic material havingthermoplastic properties and is preferably provided with an outwardlyconvex lens section 3|, the periphery of which is provided with arearwardly turned flange 1. The outer surface of the flange l defines agroove 8 extending around the periphery of the crystal and the outersurface of the flange l is beveled radially inwardly as at 9 and Illaway from the edges of the groove so that the crystal shown in Figs. 2and 1 may be pressed into the opening defined by the flange 5 of thebezel either from the inside or outside of the bezel. The crystal shownin Fig. 3 is beveled on one side of the groove only at IOA.

The crystal 3 and the opening in th flange 5 of the bezel are preferablyso proportioned in their unstressed and initially prepared stage thatwhen the crystal is pressed into the bezel it will be slightly flexed orplaced under strain and assume the position shown in full lines in Fig.4 in which the flange 1 is compressed radially inwardly of the bezel sothat the inner surface of the flange 5 does not seat accurately with thebottom of the groove 8 in the crystal. I then place the bezel andcrystal on a suitable support II as shown in Fig. 6 within the coils l2of an induction heater. When the coils I2 are energized with a highfrequency current from the alternator 13, the metal of the bezel isheated sufiiciently by induction by well known principles to soften theplastic of the flange 1 so that the stresses in the crystal cause theflange to expand into the final position shown in Fig. 2 and by thedotted lines in Fig. 4 and cause the plastic of the crystal to be sealedtightly to the flange 5 of the bezel. After thus sealing the crystal tothe bezel it is obviously impossible for the crystal to be shaken orjarred from the bezel and impossible for dirt or moisture to enter thewatch case between the crystal and bezel.

In the modified form of crystal and bezel shown in Fig. 3 the flange ofthe crystal is beveled only as at IUA and arranged to be inserted intothe bezel from the outside, it being impractical to press the straightedge 9A outwardly from the inside of the bezel. The example of thiscrystal shown in Figs. 2 and 4 may be pressed inwardly or outwardlythrough the bezel opening but I prefer to press the crystal inwardlysince any scratches which may occur on the beveled edges l0 and 1A arethen concealed within the bezel leaving the outside of the crystalunmarred. In each form of the crystal the grooves on the crystal flangeengage the bezel so that it is impossible to press the crystal inwardlyagainst the face of the watch and thus damage the movement.

I have thus described two highly practical commercial embodiments of mycrystal and bezel together with the steps for assembling them. A thirdform of my crystal assembly is illustrated in Fig. 5. The flange IE onthis crystal is beveled to the rear as at B and preferably but notnecessarily provided with a shoulder l4 forming a stop to limit thedistance the crystal may be pressed through the bezel flange 5 from thefront. The front edge of the crystal flange may be beveled or not asdesired as shown at 9B.

Aside from the shoulder [4, which is optional, the outside of thecrystal flange is ungrooved in its initially prepared form. When thecrystal is pressed into the bezel it is stressed and bowed into theposition shown in an exaggerated manner in full lines in Fig. 5. Whenthe bezel is heated as previously described localized heat and pressurewill be applied to the crystal along the inner edges of the bezelflange. The crystal will become sufficiently plastic along its line ofcontact with the bezel to flow around the edges of the bezel flange andassume the position shown by the dotted lines in Fig. 5. The crystal andbezel thus form their own tongue and groove sealing connections.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a metallic bezel having a radiallyinwardlyprojecting flange defining a crystal opening, providing a crystal ofthermoplastic material having a domed lens portion with a rearwardlyextending flange formed therearound, forming a radially outwardlyopening groove in said crystal flange completely therearound and formingouter surfaces on said flange sloping radially inwardly from said groovewith the radially outer edges of said surfaces and the base of saidgroove of slightly larger radial dimension than the corresponding,radial dimension of said opening, pressing said crystal inwardly throughsaid opening until said bezel flan e. registers with the said groove andwith said crystal in stressed condition, and subjecting said bezel andcrystal to induction heating to cause said crystal flange to be softenedand sealed to said bezel flange and to relieve the stressed condition ofsaid crystal, said induction heating being applied circumferentiallyexteriorly of the bezel and crystal flanges to facilitate softening ofthe thermoplastic material only where said flanges contact.

2. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a metallic bezel having a radially inwardlyprojecting flange defining a crystal opening, providing a crystal ofthermoplastic material having a domed lens portion with a rearwardlyextending flange formed therearound, forming a radially outwardlyopening groove in said crystal flange completely therearound and formingouter surfaces on said flange sloping radially inwardly from said groovewith the radially outer edges of said surfaces and the base of saidgroove of slightly larger radial dimension than the corresponding radialdimension of said opening, pressing said crystal outwardly through saidopening 'until said bezel flange registers with the said groove and withsaid crystal in stressed condition, and subjecting said bezel andcrystal to induction heating to cause said crystal flange to be softenedand sealed to said bezel flange and to relieve the stressed condition ofsaid crystal.

3. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a metallic bezel having a radially inwardlyprojecting flange defining a crystal opening, providing a crystal ofthermoplastic material having a domed lens portion with a rearwardlyextending flange formed therearound, forming a radially outwardlyopening groove in said crystal flange completely therearound and formingan outer surface sloping radially inwardly from an edge of said groovewith the radially outer edge of said surface and the base of said grooveof slightly larger radial dimension than the corresponding radialdimension of said opening pressing said crystal and said surface throughsaid opening until said bezel flange registers with the said groove andsubjecting said bezel and crystal to heating to cause said crystalflange to be softened and sealed to said bezel flange.

4. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a bezel having a radially inwardly projectingflange defining a crystal opening, providing a crystal of thermoplasticmaterial having a domed lens portion with a rearwardly extending flangeformed therearound, forming a radially outwardly extending shoulder onthe outside of said crystal flange and completely therearound andforming an outer surface sloping radially inwardly from said shoulderwith the inner edge of said shoulder of greater radial dimension thanthe corresponding radial dimension of said flange, pressing the slopingsurface of said crystal through said opening until said bezel flangeseats against said shoulder, and subjecting said bezel and crystal toheating to cause said crystal flange to be softened and sealed to saidbezel flange, said heat being applied to said bezel and crystal flangescircumferentially thereof and adjacent thereto to facilitate softeningthe thermoplastic material of the crystal flange only where said flangescontact.

5. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a bezel having a crystal opening. providing acrystal of thermo-plastic material having a lens portion and arearwardly turned flange therearound, said crystal flange in itsinitially prepared form having an outer portion of slightly largerdiametrical measurement than the corresponding diametrical measurementof said crystal opening and a beveled surface sloping radially inwardlyfrom said outer portion, said crystal flange also having a shoulderopening toward said beveled portion, pressing said bevel portion of saidflange through said opening to mutually and oppositely stress said bezeland crystal and seat said bezel against said shoulder, and subjectingsaid bezel and crystal to heat with the greatest intensity at andadjacent the circumference of the bezel opening and crystal flange tocause said crystal flange to be plasticized and deformed only at andclosely adjacent the edge of the bezel opening.

6. The method of assembling a watch crystal and bezel which comprisesthe steps of providing a bezel having a crystal opening, providing acrystal of thermoplastic material having a lens portion and a rearwardlyturned flange therearound, said crystal flange in its initial preparedform having an outer portion of slightly larger diametrical measurementthan the corresponding diametrical measurement of said crystal opening,pressing said flange through said opening to mutually and oppositelystress said bezel and crystal, and subjecting said bezel and crystal toheat with the greatest intensity at and adjacent the circumference ofthe bezel opening and crystal flange to cause said crystal flange to beplasticized and deformed only at and closely adjacent the edge of thebezel opening.

OTTO A. STARKE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,133,780 Ames Mar. 30, 19151,216,636 Wehinger Feb. 20, 1917 1,288,309 Wachter Dec. 17, 1918 NumberNumber 15 100,735 204,004 774,880

Name Date Porter May 1, 1928 Lindhe July 3, 1934 Schmalz Nov. 20, 1934McArthur July 21, 1936 Hinds Nov. 3, 1936 Ronci Aug. 2, 1938 DutcherJan. 9, 1940 Marti Jan. 12, 1943 Spencer Oct. 16, 1945 Falkoff Mar. 16,1948 FOREIGN PATENTS Country Date Great Britain Nov. 30, 1916Switzerland July 1, 1939 France Oct. 1, 1934

